Footwear with a hybrid outsole structure

ABSTRACT

A hybrid outsole construction comprises high-density carbon rubber molded to low-density blown rubber, providing increased flexibility, cushion, and comfort while maintaining durability, traction, and shock absorbency of the footwear. In accordance with another aspect of the present invention, the hybrid outsole construction is stitched to the upper layers of the footwear, for example using a welt.

[0001] This application claims the priority of U.S. Provisional PatentApplication No. 60/327,139, filed Oct. 3, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to footwear, particularly to footwear tobe used in a rugged environment, of lighter weight, additional comfort,and durability.

[0004] 2. Description of Related Art

[0005] A principal goal in shoe design is to design footwear that issturdy enough to protect the wearer's feet, yet flexible enough toprovide for comfortable walking. This is particularly true for ruggedfootwear such as work boots or hiking boots, where comfort is oftencompromised in a design for well-built footwear that can withstand harshconditions.

[0006] The outsole of rugged footwear is designed to resist wear,provide durability, traction and absorb shock. Commonly, the outsolematerial is made of high-density carbon rubber, which is a relativelyheavy and durable but stiff material. High-density carbon rubberprovides very little in the area of flexibility and cushion. Thus, theconstruction of an outsole of a rugged footwear must take into accountthe weight, flexibility and durability of materials used in providingthe necessary comfort and strength to the footwear.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to a hybrid outsoleconstruction comprised of high-density carbon rubber and low-densityblown rubber, providing increased flexibility, cushion, and comfortwhile maintaining durability, traction, and shock absorbency of thefootwear. Unlike prior art outsole construction, the present inventionmakes use of a hybrid structure to manufacture the outsole. High-densitycarbon rubber molded to low-density blown rubber comprises the hybridoutsole construction.

[0008] One aspect of the invention contains low-density blown rubber foradded cushioning throughout the outsole as well as high-density carbonrubber for durability, especially in high-wear areas like the heel. Amaterial for the low-density blown rubber should be flexible, such asEMAX. EMAX provides the desired flexibility, increased cushion, andlighter weight. Ethylene-vinyl acetate (EVA) can also be used instead ofthe blown rubber. Other low density, resilient synthetic plastic foammaterials may be used, such as polyurethane, polyethylene andpolyethylene vinyl acetate.

[0009] The use of low-density blown rubber, made by injecting air into arubber compound, is well known in prior art associated withfitness-related footwear. No prior art, however, suggests the use oflow-density blown rubber for providing increased agility and padding inrugged footwear like work boots.

[0010] Low-density blown rubber, however, is less durable against wearthan high-density carbon rubber. High-density carbon rubber moldedaround the EMAX, exhibits good wear resistance characteristics andpreserves the strength and efficacy of the footwear. In accordance withanother aspect of the present invention, the hybrid outsole constructionis stitched to the upper layers of the footwear, for example using awelt.

[0011] In another aspect of the present invention, the hybrid outsoleconstruction includes providing the high-density carbon rubber layerwith holes to expose the underlying low-density blown rubber. Portionsof the exposed low-density blown rubber can extend through the holes tobe formed into structures such as treads.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0012] The present invention will be more clearly understood whenconsidered in conjunction with the accompanying drawings. In thefollowing drawings, like reference numerals designate like or similarparts throughout the drawings.

[0013]FIG. 1 is a right side view of a footwear incorporating a hybridoutsole construction in accordance with one embodiment of the presentinvention.

[0014]FIG. 2 is a cross sectional view of the footwear shown in FIG. 1,taken along line 2-2.

[0015]FIG. 3 is a bottom view of the footwear shown in FIG. 1.

[0016]FIG. 4 is a side view of one embodiment of a three-quarter-weltcup heel footwear showing the various components of the footwearincluding the hybrid outsole construction with exposed low-density blownrubber arch.

[0017]FIG. 5 is a rear heel-sectional view taken along line 5-5 in FIG.4.

[0018]FIG. 6 is a front toe-sectional view taken along line 6-6 in FIG.4.

[0019]FIG. 7 is a side view of another embodiment of a lightweightwelted footwear showing the various components of the footwear includingthe hybrid outsole construction, with high-density carbon rubberundersurface.

[0020]FIG. 8 is a rear heel-sectional view taken along line 8-8 in FIG.7.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] The present description is the best contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating general principles of the invention and should not be takenin a limiting sense.

[0022]FIG. 1 illustrates a right side view of a footwear or shoe 70incorporating a hybrid outsole construction 75 in accordance with oneembodiment of the present invention. The footwear 70 comprises an upperportion 80 and the hybrid outsole construction or the lower outsoleportion 75. The upper portion 80 is shaped to receive the right foot ofa wearer and to secure the right foot of the wearer within the upperportion 80. The lower outsole portion 75 is coupled to the upper portion80, and is adapted to support the weight of the wearer on top, and iscapable of traction against rough outside contact surfaces on bottom.The lower outsole portion 75 comprises an outer sole layer 85 and aninner sole layer 90. The outer sole layer 85 is formed from asubstantially wear resistant material, such as high-density carbonrubber. The inner sole layer 90 is disposed between the upper portion 80and the outer sole layer 85. The inner sole layer 90 is formed from asubstantially resilient cushioning material that is substantially softerthan the wear resistant material forming the outer sole layer 85. Theresilient material can be low-density blown rubber, such as EMAX, EVA,polyurethane, polyethylene or polyethylene vinyl acetate. The loweroutsole portion 75 can also comprise an upper sole layer 95 disposedbetween the upper portion 80 and the inner sole layer 90. The upper solelayer 95 can be formed from the same wear resistant material, such ashigh-density rubber. The inner sole layer 90 is therefore sandwichedbetween the upper sole layer 95 and the outer sole layer 85.

[0023] The outer sole layer 85, the inner sole layer 90, and the uppersole layer 95 are coextensive along their lengths and widths. As shownin FIG. 1, the inner sole layer 90 is exposed along its perimeter sides.In some embodiments of the present invention, the exposed sides of theinner sole layer 90 allow the inner sole layer 90 to deform or expandlaterally as the wearer applies vertical pressure to the lower outsoleportion 75. The amount of deformation will depend on the resilience ofthe inner sole layer material 90. In some embodiments of the presentinvention, the inner sole layer 90 will not substantially deform underapplication of vertical pressure.

[0024] In the embodiment shown in FIG. 1, the inner sole layer 90 has avariable thickness along its length. The inner sole layer 90 is thickerat a heel section 100 of the lower outsole portion 75 than at a toesection 105 of the lower outsole portion 75. Since vertical pressure canbe greatest at the heel section 100, the additional thickness at theheel section 100 allows for additional cushion at the heel section 100to provide additional wearer comfort. In some embodiments of the presentinvention (not shown), the thickness of the inner sole layer 90 isuniform along its length.

[0025] The lower outsole portion 75 may be assembled to the upperportion 80 using a welt construction, such as the American Goodyear welt110. The American Goodyear welt 110 is used for heavy-duty shoeconstruction, such as a work boot or hiking boot. The welt constructionutilizes treated cotton twine to stitch the welt 110 to the upperportion 80 and to the lower outsole portion 75. As shown in FIG. 1, thewelt 110 can run around the entire perimeter of the upper portion 80 andthe lower outsole portion 75. Alternatively, the welt can run around thefront perimeter of the toe area and approximately three-quarters theinner and outer length of the footwear ending at the cup heel (notshown).

[0026]FIG. 2 is a cross sectional view of the footwear 70 shown in FIG.1, taken through line 2-2. The outer sole layer 85 comprises one or moreholes 115 defined through the layer 85. The holes 115 expose theunderlying inner sole layer 90, allowing portions of the inner solelayer 90 to extend and be formed through the holes 115. For example,portion 92 of the inner sole layer 85 can be formed into a tread.

[0027]FIG. 3 illustrates a bottom view of the footwear 70 shown inFIG. 1. The outer sole layer 85 includes a plurality of treads 87 forcontact with the ground. The treads 87 can have any shape and patternthat allows for optimum traction with the ground. FIG. 3 alsoillustrates a plurality of treads 92 formed from portions of the innersole layer 90 exposed through the holes 115 in the outer sole layer 85.Treads 92 and 87 form a contact surface with the ground. As treads 92contact with the ground, the more resilient treads 92 can provideadditional impact absorption, while the more wear resistant treads 87can provide sufficient traction with the ground.

[0028]FIG. 4 illustrates a side view of one embodiment of the presentinvention by way of illustration only and not by limitation, athree-quarter-welt cup heel footwear 10 incorporating a hybrid outsoleconstruction 14. It is noted that the illustration shows the right sideof the footwear. The three-quarter-welt cup heel footwear 10 is made ofan upper 12 that is created to conform to the shape of the right foot ofthe wearer, and the hybrid outsole 14 for support of the weight of thewearer on top and for traction against rough outside contact surfaces onbottom. The hybrid outsole 14 is comprised of layers of differentmaterials: a wear resistant layer of high-density carbon rubber (outersole layer) 16 trimmed at the edges, and a relatively soft, cushionlayer of low-density blown rubber (inner sole layer) 18, such as EMAX,untrimmed and set back from the outsole sidewall, which is made of thehigh-density carbon rubber 16. Other low density, resilient syntheticplastic foam materials may be used in place of EMAX, such as EVA,polyurethane, polyethylene and polyethylene vinyl acetate.

[0029] The hybrid outsole construction 14 is achieved by molding thehigh-density carbon rubber 16 around certain areas of previously createdlow-density blown rubber 18. High-density carbon rubber 16 bounds thelow-density blown rubber 18 on all sides (e.g., underneath the upper 12,at the toe and heel areas, and the bottom), but not on the lateral sidesand the underside of an arch area 28. Without high-density carbon rubberunderneath the arch 28, the footwear 10 can be more flexible to thewearer's movement.

[0030] In some embodiments of the present invention, because thelow-density blown rubber 18 is not bound on all sides and because it isset back or recessed from the outsole sidewall, space is provided toallow the low-density blown rubber 18 to substantially deform or expandlaterally as vertical pressure (i.e., under the weight of the wearer) isapplied to the hybrid outsole 14. Further, the low-density blown rubber18 in the arch area 28 substantially deforms into the space beneath thearch area 28 when vertical pressure is applied to the hybrid outsole 14.When the pressure is removed, the low-density blown rubber 18 recoversits shape and once again is recessed from the outsole sidewall. In someembodiments of the present invention (not shown), the low-density blownrubber 18 does not substantially deform under the vertical pressure.

[0031] The hybrid outsole 14 may be assembled to the upper 12 using awelt construction, such as the American Goodyear welt 20, which utilizesstitching 22, with treated cotton twine, the welt to the upper 12 andthe outsole 14 (e.g., for a heavy duty shoe construction, such as a workboot or hiking boot). The welt 20 runs around the front perimeter of thetoe area and approximately three-quarters the inner and outer length ofthe footwear 10 ending at the cup heel 24.

[0032]FIG. 5 illustrates a rear heel-sectional view of FIG. 4 displayingthe hybrid outsole 14 and its components: the high-density carbon rubber16, which is trimmed at the edges of the footwear; and the low-densityblown rubber 18, which is untrimmed and recessed from the high-densitycarbon rubber 16 sidewall. FIG. 5 shows the state in which thelow-density blown rubber 18 expands laterally to a convex profile,acting as a cushion when vertical weight is applied. When the weight isremoved, the low-density blown rubber 18 contracts back to its originalposition, with the lateral edge of the rubber 18 in a concave profile(see dotted line 17). The cup heel 24 and the high-density carbon rubber16 of the hybrid outsole 14 are one continuous piece of rubber. The cupheel 24 may be cement lasted and stitched.

[0033]FIG. 6 illustrates a front toe-sectional view of FIG. 4 showingthe hybrid outsole 14 consisting of high-density carbon rubber 16 andlow-density blown rubber 18. As shown in FIG. 6, when vertical pressureis applied to the hybrid outsole 14, the low-density blown rubber 18expands laterally here as well, forming a convex profile. When verticalpressure is released, the sidewall of the rubber 18 contracts to aconcave profile 17.

[0034]FIG. 7 illustrates a side view of another embodiment of a hybridoutsole 54, a lightweight welted footwear 50. The hybrid outsole 54 iscomprised of trimmed high-density carbon rubber (outer sole layer) 56and untrimmed, recessed, low-density blown rubber (inner sole layer) 58,such as EMAX. The high-density carbon rubber 56 covers the low-densityblown rubber 58 in certain areas: at the top, bottom, front and back,but not on the sides. The low-density blown rubber 58 is able tosubstantially deform and expand laterally as pressure is appliedvertically to the hybrid outsole 54. When the pressure is removed, thelow-density blown rubber 58 will contract to its original state.Alternatively, the low-density rubber 58 does not substantially deformunder the applied pressure.

[0035] The hybrid outsole 54 is assembled to the upper 52 with a welt 60and treated cotton twine stitching 62. The stitching 62 extends throughthe hybrid outsole 54, the welt 60, and the upper 52. The welt 60 runscompletely around the lightweight welted footwear 50.

[0036]FIG. 8 illustrates a rear heel-sectional view of FIG. 7 displayingthe trimmed high-density carbon rubber 56 and the untrimmed, recessed,low-density blown rubber 58 comprising the hybrid outsole 54. Whenvertical pressure is applied to the hybrid outsole, the low-densityblown rubber 58 expands laterally until the pressure is removed,retracting back to a convex profile 17.

[0037] While the invention has been described in detail with respect tothe illustrated embodiments in accordance therewith, it will be apparentto those skilled in the art that various changes, modifications,substitutions, alterations and improvement may be made without departingfrom the scope and spirit of the invention as defined by the appendedclaims.

What is claimed is:
 1. A shoe including an upper portion and an outsoleportion coupled to the upper portion, the outsole portion comprising: anouter sole layer formed from a substantially wear resistant material fortraction on a walking surface, wherein the outer sole layer includes ashaped hole defined through the outer sole layer; and an inner solelayer formed from a substantially resilient cushioning material, whereinthe inner sole layer is disposed between the outer sole layer and theupper portion, wherein a portion of the inner sole layer extends throughthe shaped hole in the outer sole layer.
 2. The shoe of claim 1, whereinthe outer sole layer includes a plurality of treads, and wherein theportion of the inner sole layer extending through the shaped holedefines a tread.
 3. The shoe of claim 2, wherein the inner sole layercomprises a heel section and a toe section, wherein the heel section issubstantially thicker than the toe section.
 4. The shoe of claim 1,wherein the upper portion and the outsole portion are coupled bystitching a welt to the upper portion and the outsole portion.
 5. Theshoe of claim 3, wherein the sides of the inner sole layer are exposed,so to allow the inner sole layer to deform out through the sides of theouter sole layer under the weight of a wearer.
 6. The shoe of claim 5,further comprising an upper sole layer disposed between the upperportion and the inner sole layer.
 7. The shoe of claim 6, wherein thewear resistant material comprises carbon rubber, and the resilientmaterial comprises blown rubber.
 8. A footwear comprising: an upperportion; and a lower portion coupled to the upper portion, said lowerportion having a toe section and a heel section, and comprising anoutsole portion having a hybrid structure that includes an outer layerfor traction on a walking surface and made of a wear resistant material,and an inner layer for cushioning made of a resilient material softerthan the wear resistant material, wherein the outer layer coversentirely the front of the toe section and rear of the heel section ofthe inner layer, but exposing lateral sides of the inner layer.
 9. Thefootwear as in claim 8, wherein the lower portion defines an arch area,at which the outer layer exposes the inner layer.
 10. The footwear as inclaim 8, wherein the exposed lateral sides of the inner layer has aconvex profile in the absence of the weight of a user, and a concaveprofile under the weight of the user.
 11. The footwear as in claim 8,wherein the upper portion and the lower potion are coupled by stitching.12. The footwear as in claim 11, wherein the upper portion and the lowerportion are coupled by stitching a welt to the upper portion and lowerportion.
 13. The footwear as in claim 8, wherein the exposed lateralside of the inner layer is recessed from an edge of the outer layer. 14.The footwear as in claim 8, wherein the resilient material comprisesblown rubber, and the wear resistant material comprises carbon rubber.15. A footwear comprising: an upper portion; and a lower portion coupledto the upper portion, and comprising an outsole portion having a hybridstructure that includes an outer layer for traction on a walking surfaceand made of a wear resistant material, and an inner layer for cushioningmade of a resilient material softer than the wear resistant material;wherein the upper portion is coupled to the lower portion by stitching awelt to the upper portion and the lower portion.
 16. The footwear as inclaim 15, wherein the inner layer includes an exposed lateral siderecessed from an edge of the outer layer.
 17. The footwear as in claim15, wherein the exposed lateral side of the inner layer has a convexprofile in the absence of the weight of a user, and a concave profileunder the weight of the user.
 18. The footwear as in claim 15, whereinthe resilient material comprises blown rubber, and the wear resistantmaterial comprises carbon rubber.
 19. The footwear as in claim 15,wherein the lower portion defines an arch area, at which the outer layerexposes the inner layer.